Many of the older irrigation canals are prone to leakage since they are formed with a compacted silt bottom and sloped sides. In some locations, a canal may run through extremely porous material resulting in serious leakage problems of yet greater concern.
One method for repairing such leaking canals is to install an impermeable lining in the canal. Heretofore this was not possible while water continued to flow in the canal. Thus the water would have to be diverted or retained while the lining was installed which meant that some areas would be without water during the lining process.
In the application entitled "Method and Apparatus for Lining a Canal", Ser. No. 395,811 filed Aug. 18, 1989, now U.S. Pat. No. 4,954,019 a method and apparatus for lining a canal is described. In the device of the above-identified application, a method and means is described for lining and paving the irrigation canal while water was flowing therein. The apparatus of the above-identified application comprises an elongated frame means which extends transversely across the canal and which has propelling track members at the opposite ends thereof to propel the frame means along the length of the canal. A concrete laying mechanism or concrete paver is supported on the frame means and is designed to lay concrete on at least a portion of one of the sides of the canal and on at least a portion of the bottom of the canal as the frame means is moved along the length of the canal. Prior to the concrete being placed in the canal, a flexible sheet material is positioned on the bottom and sides of the canal with the concrete being placed thereon.
In the method and means of the above-identified application, it is necessary for the bottom and the sides of the canal to be trimmed and/or filled to enable the flexible sheet material and concrete to be placed on a substantially smooth surface at the desired grade. In other words, the sheet laying apparatus and the concrete paver are designed to lay the sheet material and concrete on a relatively even surface having a predetermined grade. Inasmuch as water is flowing in the canal during the trimming operation, it is difficult to monitor the trimming apparatus since the trimming apparatus is normally operating beneath the water making it difficult to achieve the desired grade for the bottom and the sides of the canal.
A canal paving machine is described in U.S. Pat. No. 4,360,293 which is designed to trim the bottom and sides of the canal and to place a layer of concrete thereon. However, the machine of U.S. Pat. No. 4,360,293 employs a trimming apparatus which is of a fixed configuration which must be replaced when canals of different sizes and grades are being trimmed. Further, the trimming apparatus of U.S. Pat. No. 4,360,293 is designed to trim a canal wherein water is not flowing therein. Additionally, the machine of U.S. Pat. No. 4,360,293 does not include any means for filling low spots in the canal bottom or sides.
It is therefore a principal object of the invention to provide a machine for trimming a canal.
Still another object of the invention is to provide a machine for trimming a canal wherein the trimming operation is conducted while water is flowing in the canal.
Still another object of the invention is to provide a canal trimming machine which includes means for filling low spots in the canal.
Still another object of the invention is to provide a canal trimming machine which includes guidance means for the trimmer so that the canal will be trimmed to a precise grade.
Yet another object of the invention is to provide a canal trimming machine including a guidance means which may be modified to conform to different canal grades.
Still another object of the invention is to provide a canal trimming machine including a guidance means which automatically compensates for downward deflection of the supporting structure as the trimmer moves longitudinally thereon.
Still another object of the invention is to provide a canal trimming machine including means for quickly and easily raising the trimmer with respect to the canal to enable the trimmer to be returned to its starting position.
Still another object of the invention is to provide a canal trimming machine which includes means for trimming "high" spots in the canal and means for filling low spots in the canal.
These and other objects will be apparent to those skilled in the art.